[ios] Remove the unused ios_automatically_manage_certs flag.

Bug: 994873
Change-Id: I814dbb66c22efda67c31f0827c3f1f251ae263bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1394435
Reviewed-by: Rohit Rao <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Commit-Queue: Justin Cohen <[email protected]>
Auto-Submit: Justin Cohen <[email protected]>
Cr-Commit-Position: refs/heads/master@{#687924}
6 files changed